8th HEAD Meeting, 8-11 September, 2004
Session 17 Neutron Stars and X-ray Binaries
Poster, Thursday, September 9, 2004, 9:00am-10:00pm

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[17.26] X-ray Observations of the Galatic Blackhole Candidate XTE J1859+226

K. Yamaoka, M. Uzawa, M. Arai, A. Yoshida (Dept. of Physics and Mathematics, Aoyama Gakuin University)

We present the results of X-ray observations of the Galactic microquasars XTE J1859+226 in the1999 outburst with ASCA, RXTE and Beppo-SAX. The source was initially in the low/hard state, then in the very high state and high/soft state, finally returned to the low/hard state. This behaviour was the same as canonical blackhole candidates. Detailed X-ray spectral analysis shows that during the high/soft state the innermost radius derived from MCD model was almost constant at about 50 km assuming an inclination angle at 60 degree. From this results, we estimated the blackhole mass of XTE J1859+226 at 7 Msun. We also fitted the energy spectra with general relativistic accretion disk model (GRAD model: Ebisawa et al. 1994), which gives us consistent results. However, innermost radious during the very high state varies significantly because powerlaw component might be very strong relatively to the soft component as many authors pointed out. In this paper, we will investigate that there is a possibility of constancy of innermost radius.

The author(s) of this abstract have provided an email address for comments about the abstract: yamaoka@phys.aoyama.ac.jp

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